The present invention relates to windshield wiper systems and more particularly, to electronic control apparatus for controlling the operation of an electric windshield wiper motor to simultaneously permit a number of desirable windshield wiper system features to be realized with a circuit having a minimum "parts" count.
It has long been recognized that under certain driving conditions, such as with light rain or splashing from other vehciles, a vehicle windshield may rapidly alternate between being wet and dry. When such conditions exist, continuous wiper operaiton may cause smearing on the windshield, whereas intermittent wiper operation can provide adequate windshield clearing or cleaning without smearing. Preferably with such an intermittent wiping system, the dwell period between successive wipes may be manually controlled by the vehicle driver to accommodate the particular road conditions.
It is also recognized that it is desirable in a windshield wiper system to provide means for manual and/or automatic activation of a windshield washing and wiping operation to permit a windshield to be adequately cleaned to maximize visibility for the driver. Such systems preferably must operate in coordination with the continuous and/or intermittent wiping controls.
In all such wiper systems, it is desirable for reasons of economy that the control apparatus be implemented with a circuit having a minimum number of relatively inexpensive component parts. However, even though it is desirable to reduce the parts count, it is essential that quality of the overall wiper system performance not be reduced.
The present inventor is the patentee under a plurality of prior U.S. patents relating to windshield wiper systems and related control apparatus, including the following numbered U.S. Pat. Nos.: 3,351,836; 3,483,459; 3,564,374; 3,581,178; 3,582,747; 3,728,603; 3,774,091; and 3,796,936, the disclosures of which are hereby adopted by this reference.